Snubbing units are known in the oil and gas industry for facilitating access to a well which is under pressure including, for example, well operations such as well completions. A snubbing unit manipulates various tubular components such as pipe, tubing, and bottom hole assemblies (BHA) in and out of a well while controlling the well under pressure. However, wellhead components are not conventionally equipped to deal with the manipulation of tubular components therethrough. Therefore, additional hardware, in cooperation with the snubbing unit, provides additional sealing and physical handling components, which are required to handle tubular components, these being either heavy tubular components which tend to fall into the well, termed “pipe heavy”, or which can be upwardly energized for ejection from the well under pressure, termed “pipe light”. Generally, a snubbing unit employs stationary (lower) and traveling (upper) slip assemblies, opposingly oriented, to releasably and controllably shift tubulars into and out of the well through a wellhead despite the possibility of either heavy tubular loads, which urge the tubular to fall into well, or the pressure-generated forces on the tubulars, which urge the tubular out of the well. The snubbing unit is installed above an existing wellhead seal and incorporates its own seals to seal the tubulars as they are introduced or removed from the wellhead.
Snubbing units are rigged up to perform their required operation and rigged out thereafter. Most conventional snubbing units fall into either rig-assist or self-contained units. Rig-assist snubbing units are typically snubbing units that are pivotally mounted to a truck and require assistance by an onsite service rig so as to winch them upright, pivoting from the truck, to a snubbing position over the wellhead. Self-contained units are typically rig-assist snubbing units, transported to site on a truck and lifted into position, over the wellhead, by a separate crane unit. During operations, self-contained snubbing units do not require the assistance from an on-site rig. For both rig-assist and self-contained snubbing units, a variety of other site equipment is required including catwalks, pipe tubs, and pipe-handlers. All of the required equipment results in large capital equipment costs, a large footprint onsite, extra crew and larger operating costs.
Further, conventional snubbing operations require personnel to be positioned adjacent the area for tubing connections, placing personnel at the highest risk, should there be an upset or release.
There is a demonstrated need for a system utilizing a minimum of extraneous equipment, personnel and increased safety for those personnel operating snubbing units.